A compound that can temporarily restore visual responses in the retina of blind mice is described in Scientific Reports this week.
Retinitis pigmentosa (RP) and age-related macular degeneration are degenerative diseases of the eye involving the loss of rod and cone photoreceptors, leading to visual impairment and, in some cases, complete blindness. Several technologies are being pursued as potential vision-restoring treatments, including compounds called photoswitches.
Photoswitches are molecules that confer light-sensitivity on neuronal ion channels in the eye and enable control of neuronal activity using light. A previously reported photoswitch called DENAQ restored retinal light responses and visual behaviours in rodent models of RP, however, a high dose was required to achieve this and the effect disappeared several days after treatment.
Richard Kramer and colleagues report the development of an improved photoswitch compound called BENAQ. In animal models, the authors found that BENAQ is 20-fold more potent than DENAQ and can restore visual responses to the retina for almost a month. BENAQ’s effects also selectively targeted blind retinas in animals while having no apparent effect on healthy retinas. It was also shown to be non-toxic in studies on mice and rabbits at concentrations ten-fold higher than required to impart light sensitivity. The authors note that these properties potentially make BENAQ suitable as a drug candidate for vision restoration in the future.